The invention relates to lighting devices. In particular, the invention relates to a flat light-emitting lighting device for illumination and backlighting in vehicles, with integrated emergency power supply, to an aircraft, to the use, to a method, to a computer program element, and to a computer-readable storage medium.
Illuminated displays for signage, for example icons or written text, are often required in the field of passenger transport, in particular in the context of aircraft or ships. Illumination that is usually used for warning signs or information, e.g. emergency exit signs, is implemented either with conventional light bulbs or LEDs. These illumination techniques are associated with a disadvantage in particular in that considerable construction depth is required in order to achieve homogeneous illumination. For applications relating to the interior illumination in vehicles, for example in aviation, it will consequently be necessary for the designer of the interior cabin to make a decision on the type of illuminated display signs already at the planning phase, because corresponding recesses are to be provided in the interior lining.
From DE 199 08 404 A1 interior illumination for vehicles with several illumination means is known. LEDs are described as possible lighting means, which are point-shaped light sources and can appear as such. In order to generate homogeneous illumination, one embodiment of DE 199 08 404 A1 describes a grid-shaped arrangement of at least 30 LEDs and recommends that a space be maintained between the LEDs and the underside of a diffusing panel. One possible space from the diffusing panel approximately equates to the space among the individual light sources. In this way the arrangement of the interior illumination described in DE 199 08 404 A1 may require a relatively deep design depth.
Furthermore, in the case of lighting devices that use LED arrays as described in DE 199 08 404 A1 the use of several lighting means may result in high energy consumption proportional to the number of LEDs. A number of between, for example, 30 and 60 LEDs results in a power consumption of between 2 and 4 watts. In this way it may not be possible to use the benefit of the lower energy requirement of the individual LEDs to advantage.
From the European patent specification EP 0 072 949 B1 an illuminated warning- or display device is known that comprises a housing, a light-transmitting light screen and a light guiding body. The display device comprises several light sources, for example miniature lights with a comparatively high power consumption per lamp of approximately 2 W. Furthermore, the display comprises a multitude of individual parts, which may result in cost-intensive manufacture and in expensive installation work if changing the glass bulb lights becomes necessary. If an emergency situation arises it is of great importance that emergency-relevant display devices such as emergency exit displays continue to be illuminated. In this way the lighting device can be supplied with current even in the case of the cable system of a vehicle having sustained damage.